Second commit

dev/input.txt

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+kamnp

dev/main.py

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+#!/usr/bin/env python3
+import sys
+import argparse
+
+
+def parse(parsiring):
+    subparsering = parsiring.add_subparsers(dest="action")
+    encode = subparsering.add_parser("encode")
+    encode.add_argument("--cipher")
+    encode.add_argument("--key")
+    encode.add_argument("--input_file")
+    encode.add_argument("--output_file")
+    decode = subparsering.add_parser("decode")
+    decode.add_argument("--cipher")
+    decode.add_argument("--key")
+    decode.add_argument("--input_file")
+    decode.add_argument("--output_file")
+    decode_without_key = subparsering.add_parser("decode-without-key")
+    decode_without_key.add_argument("--input_file")
+    decode_without_key.add_argument("--output_file")
+    return parsiring.parse_args()
+
+
+alphabet_length = 26
+
+
+def shift(c, dd):
+    if not (ord('A') <= ord(c) <= ord('Z') or ord('a') <= ord(c) <= ord('z')):
+        return c
+    base_ind = ord('a') if c == c.lower() else ord('A')
+    return chr((ord(c) - base_ind + dd) % alphabet_length + base_ind)
+
+
+def shift_text(text, k, type):
+    result_text = ['a' for _ in range(len(text))]
+    for i in range(len(text)):
+        if type == "shift_text_caesar":
+            result_text[i] = shift(text[i], k)
+        if type == "decode_vigenere":
+            result_text[i] = shift(text[i], alphabet_length - ((ord(k[i % len(k)]) - ord('a')) % alphabet_length))
+        if type == "shift_text_vigenere":
+            result_text[i] = shift(text[i], ((ord(k[i % len(k)]) - ord('a')) % alphabet_length))
+    return ''.join(result_text)
+
+
+def count_frequencies(text):
+    frequencies = [0 for i in range(alphabet_length)]
+    total = 0
+    for c in text.lower():
+        if not ord('a') <= ord(c) <= ord('z'):
+            continue
+        total += 1
+        frequencies[ord(c) - ord('a')] += 1
+    for i in range(alphabet_length):
+        frequencies[i] /= total
+    return frequencies
+
+
+def MAE(frequencies1, frequencies2):
+    error = 0
+    for i in range(alphabet_length):
+        error += abs(frequencies1[i] - frequencies2[i]) / alphabet_length
+    return error
+
+
+def decode(text, sample):
+    min_error = 10000
+    min_k = 30
+    for k in range(alphabet_length):
+        freqs = count_frequencies(shift_text(text, alphabet_length - k, "shift_text_caesar"))
+        if MAE(freqs, sample) < min_error:
+            min_error = MAE(freqs, sample)
+            min_k = k
+    return shift_text(text, alphabet_length - min_k, "shift_text_caesar")
+
+
+if __name__ == '__main__':
+    parsing = argparse.ArgumentParser()
+    arguments = parse(parsing)
+    if arguments.action == "encode":
+        if arguments.cipher == "caesar":
+            k = int(arguments.key)
+            if len(sys.argv) == 6:
+                input_txt = input()
+                print(shift_text(input_txt, k, "shift_text_caesar"))
+            else:
+                with open(arguments.input_file) as input_1:
+                    input_txt = input_1.read()
+                    input_1.close()
+                    with open(arguments.output_file, "w") as output_1:
+                        output_1.write(shift_text(input_txt, k, "shift_text_caesar"))
+                        output_1.close()
+        else:
+            k = arguments.key
+            if len(sys.argv) == 6:
+                input_txt = input()
+                print(shift_text(input_txt, k, "shift_text_vigenere"))
+            else:
+                with open(arguments.input_file) as input_1:
+                    input_txt = input_1.read()
+                    input_1.close()
+                    with open(arguments.output_file, "w") as output_1:
+                        output_1.write(shift_text(input_txt, k, "shift_text_vigenere"))
+                        output_1.close()
+    if arguments.action == "decode":
+        if arguments.cipher == "caesar":
+            k = int(arguments.key)
+            if len(sys.argv) == 6:
+                input_txt = input()
+                print(shift_text(input_txt, alphabet_length - k, "shift_text_caesar"))
+            else:
+                with open(arguments.input_file) as input_1:
+                    input_txt = input_1.read()
+                    input_1.close()
+                    with open(arguments.output_file, "w") as output_1:
+                        output_1.write(shift_text(input_txt, alphabet_length - k, "shift_text_caesar"))
+                        output_1.close()
+        else:
+            k = arguments.key
+            if len(sys.argv) == 6:
+                input_txt = input()
+                print(shift_text(input_txt, k, "decode_vigenere"))
+            else:
+                with open(arguments.input_file) as input_1:
+                    input_txt = input_1.read()
+                    input_1.close()
+                    with open(arguments.output_file, "w") as output_1:
+                        output_1.write(shift_text(input_txt, k, "decode_vigenere"))
+                        output_1.close()
+    if arguments.action == "decode-without-key":
+        with open('War_and_Peace.txt') as f:
+            sample_text = f.read()
+            f.close()
+            sample_freqs = count_frequencies(sample_text)
+            if len(sys.argv) == 2:
+                input_txt = input()
+                print(decode(input_txt, sample_freqs))
+            else:
+                with open(arguments.input_file) as input_1:
+                    input_txt = input_1.read()
+                    input_1.close()
+                    with open(arguments.output_file, "w") as output_1:
+                        output_1.write(decode(input_txt, sample_freqs))
+                        output_1.close()

dev/output.txt

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+oeqrt